Engine

ABSTRACT

A rotary combustion engine of the type comprising a housing providing a two-lobed epitrochoidal cavity in which rotates a generally triangularly-shaped piston, the sides of which cooperate with the peripheral wall of the cavity to define three variable-volume work chambers. A thermally conductive member is placed in the peripheral wall of the cavity and insulated from that wall, the member being positioned such that it has an inwardly-directed face engaged by the axially extending seals carried at the apices of the piston. One such conductive member may be placed in the peripheral wall at the portion thereof providing a transition between the compression phase and the expansion phase. Another such conductive member may be placed in the peripheral wall in advance of the exhaust port such that the exhaust gases must move therepast to be exhausted from the port.

ited States atent 1191 Linn 1 May 28, 1974 ENGINE Primary Examiner-C. J. l-lusar [76] Inventor: Wallace Leon Linn, 6705 Grosvenor Attorney Agent Frm Hod Coffey Pl, Indianapolis, Ind. 46220 221 Filed: Mar. 16, 1973 1571 ABSTRACT [21] APPL NOJ 341,983 A rotary combustion engine of the type comprising a housing providing a two-lobed epitrochoidal cavity in which rotates a generally triangularly-shaped piston, US. the sides of cooperate the peripheral wall 123/145 R, 123/148 C, 123/148 DS, 123/19 of the cavity to define three variable-volume work A chambers. A thermally conductive member is placed [51] Int. Cl. F0211 53/011 in tha peripheral wall f the cavity and insulamd f Field Of Search-w 145 R, that wall, the member being positioned such that it has 123/148 148 D5, 191 A an inwardly-directed face engaged by the axially extending seals carried at the apices of the piston. One References Clted such conductive member may be placed in the periph- UNITED STATES PATENTS eral wall at the portion thereof providing a transition 727,158 5 1903 Lang 123/145 R between 1116 compression PhaS9 and the expansion 748,011 12/1903 Remington 123 145 R p as An th r su h conductive member may be 935g; 3/1910 Pearson 123/145 R placed in the peripheral wall in advance of the exhaust 1,360,835 11/1920 12 R port such that the exhaust gases must move therepast 3,297,006 1/1967 Marshall 123 309 to be exhausted f tha port, 3,572,030 3/1971 Cuff 123/845 12 Claims, 4 Drawing Figures I I I 9 I I 2 II If I i. e

ENGINE This invention relates to rotary combustion engines, and more particularly to the provision of an auxiliary ignition system for a Wankel engine.

I have modified a conventional Wankel engine to improve its performance and to improve the exhaust emanating from that engine. An object of my invention is to provide a Wankel engine with an auxiliary ignition system which will, once the engine is running, keep the engine running even when the primary ignition system is disconnected and which will, in fact, produce a more complete combustion of the fuel mixture drawn into the engine than is produced by the primary ignition system.

A primary object of my present invention is to provide, in the peripheral wall of the trochoidal cavity of a Wankel engine, a thermally conductive member which is insulated from that wall, i.e., from the housing of the engine, such that it will be heated to a temperature well exceeding the ignition temperature of the fuel mixture under compression. Once the conductive member is heated to the elevated temperature, it will serve as an igniter of the fuel mixture. I place that conductive member in the peripheral wall in advance of the portion thereof where the admitted fuel mixture is fully compressed between one of the apex seals as the leading seal and another of the apex seals as the following seal. Thus, the member is positioned such that it is exposed by movement of the said leading seal therepast to ignite the compressed fuel mixture for expansion. In other words, the conductive member is positioned at or defines the transition between the compression phase and the expansion phase. It will be appreciated that the location of this conductive member is established to fire the compressed mixture at the desired angular position of the rotary piston.

Another object of my present invention is to place another such conductive member in the peripheral wall and insulated therefrom in the portion thereof defining the exhaust phase and in advance of the exhaust port. The combustion product or exhaust gases, and the unburned hydrocarbons in the exhaust gases, are scraped past this conductive member to be ignited.

Other objects and features of my present invention will become apparent as this description progresses.

To the accomplishment of the above and related objects, this invention may be embodied in the forms illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific constructions illustrated and described, so long as the scope of the appended claims is not violated.

In the drawings:

FIG. 1 is a transverse cross-sectional view of a Wankel engine modified to include a thermally conductive member at the transition between the compression and expansion phases;

FIG. 2 is another such view showing such a thermally conductive member in advance of the exhaust port;

FIG. 3 is a fragmentary section view showing two such thermally conductive members, one at the transition between the compression and expansion phases and another just in advance of the exhaust port; and

FIG. 4 is an enlarged fragmentary sectional view of the heated strip.

Referring particularly to the drawings, it will be seen that I have illustrated a conventional rotary combustion engine (commonly called a Wankel engine) of the type ho n. f r nstanc n S at. M 999.92? is ue Oct. 24, 1972. I will describe briefly the conventional and well-known Wankel engine structure and then describe my improvement thereon.

The illustrated rotary combustion engine comprises a stationary housing 10 providing a cavity 11 that is defined by an inwardly facing peripheral wall 12 and a pair of axially spaced side walls or end walls 14, only one of which is shown. The peripheral wall 12 is generally in the shape of a two-lobed epitrochoid or a curve parallel thereto whose center or axis is indicated at 16 where the curves minor axis 18 and the major axis 19 intersect. A power output shaft 20 extends through the cavity I1 and is journal mounted in the end wall 14 so that the axis of the shaft 20 is coincident with the axis 16 of the peripheral wall 12.

The power output shaft 20 is provided, in the cavity 11, with an eccentric 21 on which a rotor or piston 22 is mounted for rotation about the axis 24 of the eccentric, this axis 24 being parallel to and spaced apart from the axis 16 of the output shaft 20.

The Wankel rotor or piston 22 is generally in the shape of a triangle having convex faces 26 which face the peripheral wall 12 and cooperate therewith to define three variable-volume combustion chambers 28. Wankels concept is to have the piston 22 general outline correspond to the three-lobed inner envelope of a two-lobed epitrochoid peripheral wall I2. The piston 22 must carry three apex seals 29 which engage the wall 12 and side seals 30 which engage the end walls 14. The manner in which this is accomplished is well known in the automotive engine arts.

With the two-lobed peripheral wall 12 and the threelobed piston 22, there are provided the four successive phases of intake, compression, expansion and exhaust in fixed relation to th housing 10 by forcing the piston to rotate at one-third the speed of the output shaft 20. This reduction may be accomplished by a gear train comprising the illustrated internally-toothed ring gear 31 and the externally-toothed gear 32 which is concentric with the axis 16 and which is made stationary by being fixed to the housing 10. The ring gear 31, for instance, has 1% times the number of teeth as the gear 32 to provide the required speed ratio of 3:1 between the power output shaft 20 and piston 22. The fuel intake passage is indicated at 34 and the exhaust passage is indicated at 36. The fuel intake passage 34 intersects the cavity 11 to one side of and near the minor axis 18 and on one side of the major axis 19. The exhaust passage 36- is on the same side of the major axis 19 as the intake passage, but on the opposite side of and near the minor axis 18. The piston 22, in FIGS. 1 and 2, is shown in its top dead-center (TDC) position. Typically, when the piston is in that position or slightly before, ignition occurs. That is, the fuel mixture drawn into the passage 34 and compressed is ignited, forcing the piston 22 to continue to rotate while the gas is expanding. Eventually, the apex seal 29 leading the expansion passes the exhaust passageway 36 so that the burned gas mixture is expelled to the atmosphere.

In the drawings, I have illustrated coolant passageways 38, and a spark plug 40 threaded into an opening 42 in the wall 12 so that its tip 44 is exposed to the combustion chamber 28 at the position where the fuel mixture is compressed. The spark plug 40 is merely illustrative, and in accordance with my invention, other forms of ignition devices may well be used for particular applications. For instance, in place of the spark plug, a glow plug of conventional construction may be used. Since the ignition system may be used only in the starting mode, a simple piezoelectric device may be used in lieu of the spark plug.

In the drawings, the arrow 50 represents the direction of movement of the piston 22.

According to the present invention, I place a strip or strips 60 of high-temperature metal in the wall 12 and insulated from the housing by means ofa heat insulating block such as indicated at 62. While I prefer that the metal strips 60 extend axially along the wall 12, it will be appreciated that the strips may take a variety of different shapes. I have found it convenient to form a dovetail slot axially in the wall 12 and to place a conformingly-shaped ceramic insulator block 62 in that slot 64. Then, in the ceramic block itself, I] form another dovetail slot 66 and place the conforminglyshaped metal strip 60 in that slot as viewed in FIG. 4. I may insulate the axial ends of the strip 60, Le, the ends adjacent the opposing end walls 14, from the end walls. I prefer that the strip 60 cover a substantial portion of the axial depth (parallel to the axis 16) of the trochoid bore. The ceramic block 62, of course, insulates the metal strip 60 from the cooling ability of the coolant flowing through the conventional passageways 38. Thus, the metal strip 60 will be heated by'the combustion product to a temperature in the vicinity of the temperature of the exhaust gases. In a rotary combustion engine of the type illustrated, the exhaust gas temperature is in the vicinity of 900 C. Since the temperature required to ignite a fuel mixture under compression is only in the area of 350 C., once the strip 60 is heated to the elevated temperature, it will serve as an igniter of the fuel mixture. Since the unburned hydrocarbons in the fuel mixture tend to cling to the trochoidal wall 12 because of the cooling of these walls, the seals 29 will move such unburned hydrocarbons past the hot strip 60 which will ignite the hydrocarbons.

In the embodiment of FIG. 1, the strip 60 is positioned such that the leading apex seal 29 will move past it in the direction of the arrow 50 and expose it to the compressed fuel mixture approximately 12 before the piston 22 reaches the TDC position. In other words, in the embodiment of FIG. 1, the hot strip 60 will ignite the compressed fuel mixture when the piston 22 is approximately l2 before its TDC position. The strip 60, therefore, defines the transition between the compression and expansion phases of the combustion cycle.

in the embodiment of FIG. 2, the hot strip 60 with its ceramic insulator 62 is positioned in the exhaust chamber 28 a few degrees in advance of the exhaust port 26 such that the exhaust gases, and the unburned hydrocarbons contained in the exhaust gases, are scraped past the hot strip by the apex seal 29. The purpose of the strip 60 in FIG. 2, therefore, is to reduce: the contents of the unburned hydrocarbons in the exhaust gases of the engine.

In the embodiment of FIG. 3, a strip 60 is placed in a position such that it will be exposed to the compressed fuel mixture, i.e., in a firing position, as discussed inconjunction with FIG. I, while another such strip is placed such that it will be exposed to the exhaust gases as discussed in conjunction with FIG. 2.

I have constructed and successfully operated the system illustrated in FIG. I. Specifically, I have modified an existing and commercially available Wankel engine to include the strip 60 in the ceramic insulator 62 in the position shown in FIG. 1 so that the strip, when heated, will serve as an ignition system. In the modified system, I use the conventional ignition system and the spark plug 40 as well as the hot strip 60. After the engine is running, for instance, 15 or 20 seconds, I can disconnect the conventional ignition system to keep the engine running by means of the strip 60.

By testing, I have found that the Wankel engine I have modified, as illustrated in FIG. 1, has a significantly cleaner exhaust and it runs much more efficiently. Particularly, the hydrocarbon content of the exhaust is reduced an apparent 21 percent, and the carbon monoxide content of the exhaust is reduced an apparent 15.5 percent. The modification of FIG, I resulted in an apparent decrease in fuel consumption of 13 percent.

The engine I have modified to include the hot strip 60 as an igniter was a 7.1 horsepower engine. In that engine, the exposed area of the strip was about A; inch. I used a nickel chromium metal strip in a porcelain ceramic block. I believe that the ceramic block and the metal strip should provide a minimum running clearance with the seals 29.

I claim:

1. A rotary combustion engine comprising a housing providing a cavity, said cavity being bounded by an inwardly facing wall extending peripherally about an axis and axially spaced apart inwardly facing end walls, a piston disposed in said cavity for movement about said axis, said piston cooperating with said peripheral wall and end walls to define variable volume work chambers as such movement occurs, said housing providing an intake port for admitting a fuel mixture to said cavity and an exhaust port for exhausting gases from said cavity, said piston carrying axially extending seals engaging said peripheral wall, a thermally conductive member, and thermal insulating means mounting said conductive member in said peripheral wall and insulating it therefrom, said member being positioned such that it has an inwardly directed face engaged by said piston seals.

2. The invention of claim 1 in which said conductive member and said insulating means are disposed in said peripheral wall in advance of said exhaust port whereby the combustion product is scraped past said member prior to being exhausted.

3. The invention of claim 1 in which said conductive member and said insulating means are disposed in said peripheral wall in advance of the portion thereof where the admitted fuel mixture is fully compressed between one of said seals as the leading seal and another of said seals as the following seal, said member being positioned such that it is exposed by movement of said leading seal therepast to ignite the compressed fuel mixture for expansion.

4. The invention of claim 3 including a second thermally conductive member and second thermal insulating means mounting said second conductive member in said peripheral wall such that it has an inwardly directed face engaged by said piston seals, said second member and second insulating means being disposed in said peripheral wall after the portion thereof where the ignited fuel mixture is expanded after ignition and in advance of said exhaust port whereby said following seal moves the exhaust gases past said second member before they are exhausted through said exhaust port.

5. The invention of claim 1 in which said peripheral wall includes four successive peripheral portions at which intake, compression, expansion and exhaust occur successively with the intake portion including said intake port and said exhaust portion including said exhaust port, said conductive member being disposed in said exhaust portion in advance of said exhaust port.

6. The invention of claim 1 in which said peripheral wall includes four successive peripheral portions at which intake, compression, expansion and exhaust occur successively with the intake portion including said intake port and said exhaust portion including said exhaust port, said conductive member being disposed in said wall at the transition between said compression and expansion portions.

7. The invention of claim 6 including a second thermally conductive member and second thermal insulating means mounting said conductive member in said peripheral wall such that it has an inwardly disposed face engaged by said piston seals, said second conductive member being disposed in said exhaust portion in advance of said exhaust port.

8. A rotary combustion engine comprising a housing providing a cavity, said cavity being bounded by an inwardly facing peripheral wall generally in the shape of a two-lobed epitrochoid formed about a center axis and axially spaced apart inwardly facing end walls, a generally triangular piston having three sides which face the peripheral wall and cooperate therewith'to define three variable-volume work chambers as said piston rotates about said axis and opposite ends which face said end walls, said housing providing an intake port for admitting a fuel mixture to said cavity and an exhaust port for exhausting combustion product from said cavity, said piston carrying, at its apices, axially extending seals which engage said peripheral wall, said peripheral wall including four successive peripheral portions at which intake, compression, expansion and exhaust occur successively with the intake portion including said intake port and the exhaust port including said exhaust port, an axially extending thermally conductive member, and axially extending thermal insulating means mounting said conductive member in said peripheral wall and insulating it therefrom, said member being positioned such that it has an inwardly directed axially extending face engaged by said apex seals.

9. The invention of claim 8 in which said conductive member is disposed in said exhaust portion of said peripheral wall in advance of said exhaust port.

10. The invention of claim 8 in which said conductive member is disposed in said peripheral wall at the transition between said compression and expansion portions.

11. The invention of claim 9 in which said peripheral wall is formed with an axially extending dovetail slot, said insulating means including a conformingly shaped ceramic block disposed in said slot, said block having an axially extending inwardly facing surface formed, intermediate its peripheral edges, with a second axially extending dovetail slot, said conductive member being a conformingly shaped metal strip disposed in said second slot.

12. The invention of claim 10 in which said peripheral wall is formed with an axially extending dovetail slot, said insulating means including a conformingly shaped ceramic block disposed in said slot, said block having an axially extending inwardly facing surface formed, intermediate its peripheral edges, with a second axially extending dovetail slot, said conductive member being a conformingly shaped metal strip disposed in said second slot.

PO-1O5O UNITED STATES PATENT OFFICEv CERTIFICATE OF CORRECTION Pat t N 3 812 827 Dated ay 28 1974 Inventor 5 Wallace Leon Linn It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shownbelow:

r- Column 1, line 62 should read FIG. 3 is a fragmentary j sectional View showing two Column 2, line 39, "th" should be the Column 3, line 55, "exhaust port 26" should be exhaust port 36 Column 5, line 23 (Claim 7, line 4) "disposed" should be directed Column 6 line 6 (Claim 8, line 18) should read 7 port and the. exhaust portion including said exhaust port,

Signed and sealed this 24th day of September 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. I C. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A rotary combustion engine comprising a housing providing a cavity, said cavity being bounded by an inwardly facing wall extending peripherally about an axis and axially spaced apart inwardly facing end walls, a piston disposed in said cavity for movement about said axis, said piston cooperating with said peripheral wall and end walls to define variable volume work chambers as such movement occurs, said housing providing an intake port for admitting a fuel mixture to said cavity and an exhaust port for exhausting gases from said cavity, said piston carrying axially extending seals engaging said peripheral wall, a thermally conductive member, and thermal insulating means mounting said conductive member in said peripheral wall and insulating it therefrom, said member being positioned such that it has an inwardly directed face engaged by said piston seals.
 2. The invention of claim 1 in which said conductive member and said insulating means are disposed in said peripheral wall in advance of said exhaust port whereby the combustion product is scraped past said member prior to being exhausted.
 3. The invention of claim 1 in which said conductive member and said insulating means are disposed in said peripheral wall in advance of the portion thereof where the admitted fuel mixture is fully compressed between one of said seals as the leading seal and another of said seals as the following seal, said member being positioned such that it is exposed by movement of said leading seal therepast to ignite the compressed fuel mixture for expansion.
 4. The invention of claim 3 including a second thermally conductive member and second thermal insulating means mounting said second conductive member in said peripheral wall such that it has an inwardly directed face engaged by said piston seals, said second member and second insulating means being disposed in said peripheral wall after the portion thereof where the ignited fuel mixture is expanded after ignition and in advance of said exhaust port whereby said following seal moves the exhaust gases past said second member before they are exhausted through said exhaust port.
 5. The invention of claim 1 in which said peripheral wall includes four successive peripheral portions at which intake, compression, expansion and exhaust occur successively with the intake portion including said intake port and said exhaust portion including said exhaust port, said conductive member being disposed in said exhaust portion in advance of said exhaust port.
 6. The invention of claim 1 in which said peripheral wall includes four successIve peripheral portions at which intake, compression, expansion and exhaust occur successively with the intake portion including said intake port and said exhaust portion including said exhaust port, said conductive member being disposed in said wall at the transition between said compression and expansion portions.
 7. The invention of claim 6 including a second thermally conductive member and second thermal insulating means mounting said conductive member in said peripheral wall such that it has an inwardly disposed face engaged by said piston seals, said second conductive member being disposed in said exhaust portion in advance of said exhaust port.
 8. A rotary combustion engine comprising a housing providing a cavity, said cavity being bounded by an inwardly facing peripheral wall generally in the shape of a two-lobed epitrochoid formed about a center axis and axially spaced apart inwardly facing end walls, a generally triangular piston having three sides which face the peripheral wall and cooperate therewith to define three variable-volume work chambers as said piston rotates about said axis and opposite ends which face said end walls, said housing providing an intake port for admitting a fuel mixture to said cavity and an exhaust port for exhausting combustion product from said cavity, said piston carrying, at its apices, axially extending seals which engage said peripheral wall, said peripheral wall including four successive peripheral portions at which intake, compression, expansion and exhaust occur successively with the intake portion including said intake port and the exhaust port including said exhaust port, an axially extending thermally conductive member, and axially extending thermal insulating means mounting said conductive member in said peripheral wall and insulating it therefrom, said member being positioned such that it has an inwardly directed axially extending face engaged by said apex seals.
 9. The invention of claim 8 in which said conductive member is disposed in said exhaust portion of said peripheral wall in advance of said exhaust port.
 10. The invention of claim 8 in which said conductive member is disposed in said peripheral wall at the transition between said compression and expansion portions.
 11. The invention of claim 9 in which said peripheral wall is formed with an axially extending dovetail slot, said insulating means including a conformingly shaped ceramic block disposed in said slot, said block having an axially extending inwardly facing surface formed, intermediate its peripheral edges, with a second axially extending dovetail slot, said conductive member being a conformingly shaped metal strip disposed in said second slot.
 12. The invention of claim 10 in which said peripheral wall is formed with an axially extending dovetail slot, said insulating means including a conformingly shaped ceramic block disposed in said slot, said block having an axially extending inwardly facing surface formed, intermediate its peripheral edges, with a second axially extending dovetail slot, said conductive member being a conformingly shaped metal strip disposed in said second slot. 